System and method of grounding fiber storage trays

ABSTRACT

An optical fiber cable management panel includes drawer assemblies, each including a drawer slidable within a chassis. The chassis incorporates a grounding point, and the drawer assemblies are electrically connected to the grounding point by a grounding strap. The grounding strap flexes to allow the slidable movement of the drawer relative to the chassis. The strap may be folded one or more times. The strap may be bolted, welded, or otherwise conductively and non-rotatably affixed at each end to the drawer and the chassis so as to maintain a constant position within the assembly and a constant electrical connection between the drawer and the grounding point.

TECHNICAL FIELD

This disclosure concerns management of optical fiber cables. Inparticular, this disclosure relates to grounding of optical fiber cablestorage devices in the telecommunications industry.

BACKGROUND

Cable termination, splice, and storage devices are known including, forexample, devices shown in U.S. Pat. Nos. 6,438,310 and 6,504,988, bothassigned to ADC Telecommunications, Inc. Both of these patents concerndevices with slidable drawers for storage and management of the opticalfiber cables. The slidable drawers are connected to a grounded chassisvia a pair of ball bearing slides. These ball bearings provideinsufficient and unreliable grounding for active fiber and electronicsstored in the drawers. The slidable drawers may also be connected to thechassis via a non-conductive slide mechanism, or may be connected to anon-conductive portion of the chassis. So, reliance on the slidemechanism for grounding may not be effective.

The slidable drawers contain the trays that hold many strands of opticalfiber. There is a growing need for added active electronic orelectro-optical devices, such as LED driver and display combinations,optical amplifiers, or lasers to be included in the drawers. As moreactive and passive electronic and electro-optical equipment is added tothe drawers, a reliable grounding mechanism is needed.

Therefore, improvements are desirable.

SUMMARY

In one aspect, the present invention concerns an optical fiber cablemanagement system. The management system includes a chassisincorporating a grounding point and a drawer assembly slidably mountedwithin the chassis on a drawer slide. A flat grounding strap is attachedto the grounding point and the sliding drawer. The strap flexes toaccommodate the movement of the drawer along the drawer slide.

A method of grounding an optical fiber cable management panel is alsoprovided. This method includes providing a chassis incorporating agrounding point and a drawer slidably mounted within the chassis. Themethod also includes electrically connecting the grounding point to theslidable drawer with a grounding strap. Opposing ends of the groundingstrap are attached to the drawer and grounding point respectively so asallow the strap to flex. The strap flexion accommodates the movement ofthe drawer relative to the chassis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cable management panel, depicting twoclosed drawers;

FIG. 2 is a top view of the panel of FIG. 1;

FIG. 3 is a top view of the panel of FIG. 2 with one drawer in the openposition;

FIG. 4 is a top view of another possible embodiment of the cablemanagement panel with one of the drawers in the open position;

FIG. 5 is a side view of the area of the panel of FIG. 3 between thedrawer and chassis;

FIG. 6 is a side view of the area of the panel in FIG. 3 inside thedrawer and between the drawer and chassis.

DETAILED DESCRIPTION

A cable management panel or module is depicted in FIG. 1 generally at30. The panel 30 includes one or a plurality of drawer assemblies 32. Inthe one shown in FIG. 1, the panel 30 includes two drawer assemblies 32.Each of the drawer assemblies 32 includes a chassis 34 and a drawer 36slidably mounted within the chassis 34.

Each drawer 36 may include cable management structure, for example,devices for storing the cables or connecting the cables to other cablesor fiber optic devices, such as attenuators, couplers, switches, wavedivision multiplexers, splitters or splices. Each drawer 36 may alsoinclude active electronic or electro-optical devices, such as LED driverand display combinations, optical amplifiers, or lasers. Each drawer 36includes two latches 40 to secure the drawer 36 in a closed position(the position shown in FIG. 1).

Each drawer 36 includes a base 42, a front wall 44 and a rear wall 46.Note that the drawer 36 is absent of side walls, or is “side wall-free.”This structure allows for cable entry and exit and prevents cable damageduring sliding movement of the drawers 36 when accessing the cables andconnectors or other devices in the drawer 36. The base 42, front wall 44and rear wall 46 together define a storage interior 48 for holding andstoring the cables.

The chassis 34 incorporates a grounding point for electrical connectionto a facility ground, such as a bolt 54. To ground the drawer 36, therear wall 46 is electrically connected to the bolt 54 through agrounding strap 50. The grounding strap 50 is flexible and is made ofstainless steel, nickel silver, or some similar conductive flexiblematerial.

Each storage interior 48 is sized for receiving cable management and/ordistribution structures. When the drawer 36 is in the closed position,the cables and management or distribution structures in the storageinterior 48 are protected. In preferred embodiments, the distributionstructures can be conveniently mounted on a tray insert (not shown) thatdrops into the storage interior 48. Example tray inserts are shown anddescribed in U.S. Pat. Nos. 6,438,310 and 6,504,988, the disclosures ofwhich are hereby incorporated by reference. This allows for convenientstructuring of the drawer 36 to serve one or more desired functions inthe panel 30. In the embodiment illustrated, each of the drawers 36 isconstructed to be stackable and linkable to form sub-cable managementpanels 31. Such modularity also allows for ease of use for a variety ofdifferent needs for the cable management system.

Referring to FIG. 2, a top view of the cable management panel with thedrawer 36 in a closed position is shown. The grounding strap 50 isattached at each end to chassis 34 and rear wall 46 of drawer 36,respectively. This conductive attachment may be accomplished with bolts52 and 54. When the drawer 36 is in the closed position, the strap 50 iscompressed into a folded position where ends of the strap 50 approacheach other. The bolt 54 attached to the chassis 34 provides a groundingpoint for the cable management panel. Grounding may be accomplished byelectrically connecting the bolt 54 to a facility electrical ground 55.

The drawer 36 has conductive properties, and includes rear wall 46 thatin the preferred embodiment is comprised of conductive material such asmetal. The rear wall 46 is electrically connected to any electricalequipment contained within drawer 36, possibly through attachment to ametallic base of the drawer 36. One of skill in the art will recognizethat rear wall 46 need not be conductive. In this case, the metallicbase of drawer 36 or other elements requiring a ground connection may beelectrically connected to bolt 52 by a conductive wire (see, forexample, FIG. 6).

The grounding strap 50 electrically connects the drawer 36 to thechassis 34. The grounding strap 50 is attached at each end to chassis 34and rear wall 46 of the drawer 36, respectively. In the preferredembodiment, the grounding strap 50 has two legs 51 a and 51 b. The legs51 a and 51 b are separated by a bend 51 c. The legs 51 a and 51 b haveend regions 51 d and 51 e, respectively. End region 51 e is attached tothe rear wall 46 by a bolt 52. Likewise, end region 51 d is attached tothe chassis 34 by a bolt 54. The end regions 51 d and 51 e may beattached in one or more places or may be otherwise supported so thatgravity or other forces do not cause it to rotate out of a preferredposition, as shown (see also FIG. 5). Bolts 52 and 54 may be offset withrespect to each other so as to minimize the distance between rear wall46 and chassis 34 when drawer 36 is in a closed position.

Various structures or combinations of structures may be used foraffixing the strap 50 to the chassis 34 and rear wall 46 of the drawer36 in such a manner that the affixing structure maintains continuouselectrical contact and a grounding point while preventing rotation ofthe strap 50. In a preferred embodiment, bolts 52 and 54 affix the strap50 to the chassis 34 and the rear wall 46, while flanges on the rearwall 46 and chassis 34 prevent rotation out of a preferred position (asshown and discussed in FIGS. 5 and 6, below). In an alternateembodiment, a second affixing structure such as a rivet, weld, or othermechanical attachment configuration such as a lance may be used incombination with bolt 52 and/or 54 to prevent rotation of the strap 50out of a preferred position. In such an embodiment, the flanges shownand described in FIGS. 5 and 6 are optional.

In another embodiment of the present disclosure, an alternative affixingstructure may be substituted for bolt 52. For example, a rivet, weld, orother mechanical attachment configuration such as a lance may be used toattach the grounding strap 50 to the rear wall 46 of drawer 36 insteadof bolt 52. The bolt 54 is a preferred structure for attaching adiscreet grounding conductor to the facility electrical ground 55;however, alternate conductive attachment mechanisms providing agrounding point may similarly be implemented. These alternative affixingstructures may be used in combination with the flanges shown anddescribed in FIGS. 5 and 6, or any of the other structures mentionedherein for maintaining the grounding strap in a preferred position.

Referring to FIG. 3, a top view of the cable management panel with thedrawer 36 in an open position is shown. Each drawer 36 is slidablerelative to chassis 34 by way of two drawer slides 38 on opposite sidesof the chassis 34. The grounding strap 50 is flexible, and flexes into a“wishbone” shape when the drawer 36 is in an open position. Thegrounding strap 50 defines a conductive path from the drawer 36 to thegrounding point 55 when the drawer 36 is in either an open or a closedposition.

Referring to FIG. 4, a further embodiment of the present disclosure isshown, with the drawer 36 in an open position. A grounding strap 150attaches to the chassis 34 and the rear wall 46 of drawer 36. Thegrounding strap is separated into three legs 151 a, 151 b, and 151 c,respectively. The three legs 151 a, 151 b, and 151 c are separated bytwo folds 151 d and 151 e. Two regions of the grounding strap 151 a and151 c have end regions 151 f and 151 g. End region 151 f attaches to thechassis 34 with a fastener such as a bolt 54. End region 151 g attachesto the rear wall 46 with a fastener such as a bolt 52. The drawer 36 isslidable relative to the chassis 34 by way of two drawer slides 38 onopposite sides of the chassis 34. In this embodiment, the groundingstrap 150 flexes into a “z” or “double-wishbone” shape to accommodatethe drawer 36 as it slides on the drawer slides 38 into open or closedpositions.

Referring to FIG. 5, a side view of the area between the chassis 34 andthe rear wall 46 of the drawer 36 is shown for the open drawerconfiguration (see, for example, FIG. 3) in a possible embodiment of thepresent disclosure. The drawer 36 has rear wall 46 that could beconductive, and may be made from metal. The chassis has a top flange 56a and a bottom flange 56 b. The drawer 36 has a top flange 56 c and abottom flange 56 d adjacent to the rear wall. The vertical distancebetween the top flanges 56 a and 56 c and the bottom flanges 56 b and 56d is the same, and allows a grounding strap 50 to fit between theflanges. The grounding strap 50 has two legs 51 a and 51 b. The legs areseparated by a fold 51 c. The legs 51 a and 51 b have end regions 51 dand 51 e, respectively. The end region 51 e is attached to the drawer 36by a fastener 52. The end region 51 d is attached to the chassis 34 by afastener such as a bolt 54. The end regions 51 d and 51 e have a widththat corresponds to the distance between the top and bottom flanges ofthe chassis 34 and drawer 36, respectively. This prevents the groundingstrap 50 from pivoting about an axis defined by bolts 52 and 54, yetallows only two bolts to be used.

Referring to FIG. 6, a side view of the area inside the drawer 36 andbetween the chassis 34 and the rear wall 46 of the drawer 36 is shownfor the open drawer configuration (see, for example, FIG. 3) in apossible embodiment of the present disclosure. The drawer 36 has rearwall 46 that need not be conductive, and chassis 34 may also no longerbe conductive. A grounding strap 50 is attached to the drawer 36 andchassis 34 by fasteners, such as bolts 52 and 54, respectively. Anactive device 58 requiring grounding, such as LED driver and displaycombinations, optical amplifiers, or lasers, may be located within thedrawer 36. The active device 58 is attached to a wire 60 that providesan electrical connection between the device 58 and bolt 52. Bolts 52 and54 are conductive, and along with grounding strap 50 and wire 60 definea conductive path from the device 58 in the interior of drawer 36 to theexterior of the chassis 34, allowing for electrical connection to thefacility electrical ground 55. One of skill in the art will recognizethat additional wires may be connected from one or more components orconductive planes (such as the metallic base described above) in thedrawer 36 to bolt 52 to provide multiple grounding paths.

When grounding straps 50, 150 are used, grounding of the drawers 36 isthrough straps 50, 150 and bolts 52 and 54. Drawer slides 38 no longerneed to define an electrically conductive path. Drawer slides 38 can bemade from non-electrically-conductive materials if desired.

The above specification, examples and data provide a description of themanufacture and use of the composition of the disclosure. Since manyembodiments of the disclosure can be made without departing from itsspirit and scope, the invention resides in the claims hereinafterappended.

1. An optical fiber cable management system comprising: (a) a chassisincorporating a grounding point; (b) a drawer slidably mounted withinsaid chassis; (c) a drawer slide mounted within said chassis to acceptsaid drawer; (d) a flat grounding strap wherein opposing ends of saidstrap are fixed to said grounding point and said drawer such that saidstrap flexes to accommodate movement of said drawer relative to saidchassis and along said drawer slide, and wherein the grounding strap isfolded one or more times to accomplish the flexing.
 2. The system ofclaim 1, wherein the grounding strap is comprised of stainless steel. 3.The system of claim 1, wherein the grounding strap is comprised ofnickel and silver.
 4. The system of claim 1, wherein the grounding strapis fastened with fasteners near opposite ends to a back portion of theslidable drawer and the chassis, respectively.
 5. The system of claim 4,wherein the fasteners are positioned to reduce spacing between a backportion of the slidable drawer and the chassis.
 6. The system of claim4, wherein the fasteners are offset with respect to each other to reducespacing between a back portion of the slidable drawer and the chassis.7. The system of claim 4, wherein at least one fastener is a bolt. 8.The system of claim 1, wherein one or more mechanical attachmentconfigurations fasten opposite ends of the grounding strap to a backportion of the slidable drawer and the chassis, respectively.
 9. Thesystem of claim 1, wherein the grounding strap is electrically bondednear opposite ends to a back portion of the slidable drawer and thechassis, respectively.
 10. A method of grounding an optical fiber cablemanagement panel; the method comprising: (a) providing a chassisincorporating a grounding point, a drawer slidably mounted within saidchassis, and a drawer slide mounted within said chassis to accept saiddrawer; (b) electrically connecting said slidable drawer to saidgrounding point by affixing opposing ends of a flat grounding strap to arear of said drawer and said grounding point; (c) moving said slidabledrawer from a closed position to an open position, wherein saidgrounding strap flexes to accommodate movement of said drawer relativeto said chassis, and wherein the grounding strap is folded one or moretimes to accomplish the flexing.
 11. An optical fiber cable managementsystem comprising: (a) a chassis incorporating a grounding point; (b) adrawer slidably mounted within the chassis, the drawer including a rearwall; (c) a drawer slide mounted within the chassis to accept thedrawer; (d) a flat grounding strap wherein opposing ends of the strapare non-pivotally fixed to the grounding point and the rear wall suchthat the strap flexes to accommodate movement of the drawer relative tothe chassis and along the drawer slide, and wherein the grounding strapis folded one or more times to accomplish the flexing.
 12. The system ofclaim 11, wherein the strap is fixed to a back portion of the chassis.13. The system of claim 11, wherein the strap is fixed with fasteners tothe rear wall of the drawer and the chassis.
 14. A telecommunicationsequipment management system comprising: (a) a chassis including a firstplanar surface including a grounding location; (b) a drawer slidablymounted within said chassis and including a second planar surfacegenerally parallel to said first planar surface; (c) a drawer slidewithin said chassis to accept said drawer, wherein said drawer slides ina direction transverse to said first and second planar surfaces; (d) agrounding strap having a flat shape in cross-section, said groundingstrap including at least one intermediate vertex, and first and secondends mounted to said first and second planar surfaces, respectively, toelectrically ground said drawer to said chassis.
 15. The system of claim14, wherein the first and second ends and the vertex of the groundingstrap define a wishbone shape when the drawer is moved to an extendedposition relative to the chassis.
 16. The system of claim 14, whereinthe vertex is a first vertex, and wherein the grounding strap includes asecond vertex, wherein the first and second ends and the first andsecond vertexes define a double wishbone shape when the drawer is movedto an extended position relative to the chassis.